Yeah there's a lot of sticking on bass notes, and semitonal transpositions/chromatic movement, so it definitely doesn't stay in any one place and it probably is impossible to really say these songs are in a specific key signature. I guess it's straddling the line between atonal and tonal. I might not have heard anything that's definitively called atonal so I might not know what to look for, but if there is anything more atonal in the stricter sense I'd be interested in hearing it. Also need to find more composers who write this kind of thing... all the composers listed (Takenouchi, Matsuo, Fukuda, Hanzawa) specialise in this kind of thing.
Here's a couple of others
Emerald Dragon~Boss Battle
http://www.youtube.com/watch?v=hX7uKKS2ipQ
Emerald Dragon~Dungeon Battle
http://www.youtube.com/watch?v=Z47HCppRp8A